Basalt with Iron Oxidation

Hardness: 6 (Mohs scale), Color: Dark grey to black with reddish-brown oxidation, Luster: Dull to sub-metallic, Crystal structure: Aphanitic (fine-grained), Specific gravity: 2.8–3.0

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the surface of a terrestrial planet or moon. The reddish tint indicates secondary weathering (oxidation) of iron-bearing minerals like olivine or pyroxene.

Commonly used in construction as aggregate, road base, and railroad ballast. In high-quality forms, used for stone sculpture or cast basalt liners.

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.

Identify in the field by its weight (dense), dark color, and fine-grained texture. Found globally in volcanic regions. Look for reddish-brown exterior 'crusts' (called a weathering rind) as seen in this specimen.